This research project will permit the investigators to continue studies of the pathophysiology of surgical vascular disorders. Studies of the relative roles of mechanical and humoral factors in initiating the acute changes in pulmonary embolism will continue. The data obtained thus far indicate that mechanical obstruction has the major role. Studies of fluid transport in experimental lymphedema are continuing and indicate that the rate of lymph formation depends on a variety of factors, but that lymph flow is not stagnant. The role of the fibrinolytic mechanism in maintaining vessel patency is being evaluated. Studies are being performed on the interactions of platelets and heparin.